知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 频率是单位时间内完成振动的次数，是描述振动物体往复运动频繁程度的量，为了纪念德国物理学家赫兹的贡献，人们把频率的单位命名为赫兹，简称“赫”。 RAND is actually a nonprofit institution that can help increase coverage and decisionmaking by investigate and analysis. RAND's publications usually do not essentially reflect the v... https://davidl285oqs3.ssnblog.com/profile